FLUID DISPENSING APPARATUS NOZZLE HAVING WEAR-COMPENSATED VALVE SEAT MEMBER, AND RELATED METHODS
A nozzle for use with a fluid dispensing apparatus configured to dispense fluid and including a valve stem, the valve stem having a stem tip and being movable between an open position and a closed position. The nozzle includes a nozzle body and a valve seat member coupled to the nozzle body. The valve seat member includes an outer surface, an inner surface extending in a direction substantially parallel to a direction in which the outer surface extends, and a valve seat extending between the outer surface and the inner surface. The valve seat is configured to contact the stem tip in the closed position. The valve seat has a valve seat surface area, and the valve seat member is configured to maintain the valve seat surface area as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
This application claims priority to U.S. Provisional Patent Application No. 62/131,458, filed on Mar. 11, 2015, the entire disclosure of which is incorporated herein by reference.
TECHNICAL FIELDThe present invention relates generally to fluid dispensers, and more particularly, to fluid dispensers having movable valve stems.
BACKGROUNDThe process of manufacturing electronic components, such as light emitting diodes (“LEDs”), generally requires dispensing of various high viscosity fluids. Automated fluid dispensing apparatuses are often employed to meet such demands, particularly in industrial applications requiring a high throughput of electronic components.
In known fluid dispensing apparatuses, such as apparatus 1, the volume of fluid dispensed from the nozzle is a function of the amount of energy that is transferred from the valve stem to the fluid when the stem tip is lowered into contact with the valve seat. The amount of energy transferred from the valve stem to the fluid is a function, in part, of the surface area of the valve seat and the angle of contact between the valve stem and the valve seat. Therefore, varying the surface area of the valve seat and/or the angle of contact varies the amount of energy transferred from the valve stem to the fluid, which in turn varies the volume of fluid dispensed from the nozzle.
Abrasive liquid materials are often dispensed during formation of electronic components, and directly contribute to the wear of internal components of a fluid dispensing apparatus over time. For example, during an encapsulation step of LED manufacture, a mixture of abrasive yellow phosphor and a binder, such as silicone or epoxy, is dispensed onto LED dies. The valve seat of the fluid dispensing apparatus is particularly vulnerable to accelerated wear due to its direct, repeated contact with the abrasive material and the valve stem tip. The valve seat member wears with repeated use of the fluid dispensing apparatus, even when the valve seat member is formed of a hard metallic material.
Valve seat members of known fluid dispensing apparatuses, such as apparatus 1 shown in
During manufacture of electronic components, it is desirable to dispense fluids, including abrasive fluids such as LED encapsulent, with a high degree of precision and repeatability, so as to maintain consistency in the performance characteristics of the resultant electronic components produced through the dispensing operations. It is also desirable to maintain optimal dispensing performance with minimal financial resources being devoted to operational costs, such as for replacement nozzles. Accordingly, there remains a need for improvement in known fluid dispensers to address the shortcomings described above.
SUMMARYIn accordance with one embodiment, a nozzle for use with a fluid dispensing apparatus configured to dispense fluid is provided. The fluid dispensing apparatus includes a valve stem having a stem tip and is movable between an open position and a closed position. The nozzle includes a nozzle body and a valve seat member coupled to the nozzle body. The valve seat member includes an outer surface, an inner surface extending in a direction substantially parallel to a direction in which the outer surface extends, and a valve seat extending between the outer surface and the inner surface. The valve seat is configured to contact the stem tip in the closed position. The valve seat has a valve seat surface area, and the valve seat member is configured to maintain the valve seat surface area as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
In accordance with another embodiment, a fluid dispensing apparatus configured to dispense fluid is provided. The fluid dispensing apparatus includes a dispenser body, a valve stem operatively coupled to the dispenser body, and a nozzle operatively coupled to the dispenser body. The valve stem includes a stem tip and is movable between an open position and a closed position. The nozzle includes a nozzle body and a valve seat member coupled to the nozzle body. The valve seat member includes an outer surface, an inner surface extending in a direction substantially parallel to a direction in which the outer surface extends, and a valve seat extending between the outer surface and the inner surface. The valve seat is configured to contact the stem tip in the closed position. The valve seat has a valve seat surface area, and the valve seat member is configured to maintain the valve seat surface area as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
In use, a method of dispensing fluid with a fluid dispensing apparatus is provided. The fluid dispensing apparatus includes a dispenser body, a valve stem operatively coupled to the dispenser body and having a stem tip, and a nozzle operatively coupled to the dispenser body and including a valve seat member having a valve seat. The valve stem is movable between an open position and a closed position. The method includes providing the valve stem in the open position in which the stem tip is spaced from the valve seat and in which the fluid collects in a space between the stem tip and the valve seat. The method further includes moving the valve stem in a direction toward the valve seat to provide the valve stem in the closed position, and forcing the fluid with the stem tip through a passage extending through the valve seat member and the nozzle body to dispense the fluid. The method further includes, while in the closed position, contacting the valve seat with the stem tip, including contacting an upper outer edge of the valve seat member defined by the valve seat and an outer surface of the valve seat member, and contacting a lower inner edge of the valve seat member defined by the valve seat and an inner surface of the valve seat member.
Various additional features and advantages of the invention will become more apparent to those of ordinary skill in the art upon review of the following detailed description of the illustrative embodiments taken in conjunction with the accompanying drawings.
Referring to
The fluid dispensing apparatus 20 includes a dispenser body 24, a fluid inlet fitting 26 coupled to a lower portion of the dispenser body 24, and an actuating air inlet fitting 28 and a solenoid valve 30 coupled to an upper portion of the dispenser body 24. The fluid inlet fitting 26 receives a supply of liquid material from a liquid material reservoir (not shown), and directs the liquid material inwardly through the dispenser body 24 to be dispensed, as described in greater detail below. The actuating air inlet fitting 28 is adapted to receive a supply of actuating air, and the solenoid valve 30 is operable by a controller (not shown) to selectively direct the actuating air through the dispenser body 24 to actuate internal components of the fluid dispensing apparatus 20 for dispensing the liquid material, as described below.
The fluid dispensing apparatus 20 further includes a fluid chamber member 32 coupled to the dispenser body 24 and defining a cylindrical fluid chamber 34 having a central axis. The fluid chamber member 32 includes an upper chamber member portion 36 having a radially extending bore that receives the fluid inlet fitting 26 therethrough in threaded engagement. Accordingly, a fluid inlet passage 38 defined by the fluid inlet fitting 26 opens to and communicates with the fluid chamber 34 so that liquid material received through the fluid inlet fitting 26 may be directed into the fluid chamber 34.
A chamber member support plate 40 is coupled to the dispenser body 24 and includes a lower annular lip 42 defining an aperture through which a lower chamber member portion 44 extends. The lower chamber member portion 44 includes an annular recess 46 shaped to receive an upper portion of the dispensing nozzle 22 and thereby align the nozzle 22 coaxially with the central axis of the fluid chamber 34. A nozzle retaining nut 48 contacts and supports an upper portion of the nozzle 22, and threadedly engages the lower chamber member portion 44 so as to releasably couple the nozzle 22 to the fluid chamber member 32.
A valve stem 50 extends through the fluid chamber 34 and is movable along the central axis of the fluid chamber 34 between an upward open position shown in
The upper stem end 52 extends through and is coupled to a piston assembly 58 received within an air cylinder 60 defining an air chamber 62. The air cylinder 60 is defined by an inner surface of the dispenser body 24. The piston assembly 58 includes an upper piston member 64, a lower piston member 66, and a piston seal 68 positioned therebetween and adapted to sealingly contact the air cylinder 60.
A coil compression spring 70 is positioned between the upper piston member 64 and a lower end of a valve stroke adjustment assembly 72. The coil spring 70 exerts a compression spring force on the upper piston member 64 and thereby biases the valve stem 50 toward the downward closed position. The valve stroke adjustment assembly 72 includes a central adjusting screw 74 that may be rotated to selectively adjust an axial distance, referred to as “stroke,” that the valve stem 50 travels between the open position and the closed position.
A valve stem guide 76 encircles a medial portion of the valve stem 50 and maintains the valve stem 50 in coaxial alignment with the fluid chamber 34. A lower stem seal 78 is positioned axially below the valve stem guide 76 and encircles and sealingly contacts the valve stem 50 to create a liquid-tight seal that blocks liquid material from flowing upwardly from the fluid chamber 34 into the air chamber 62. An upper stem seal 80 is positioned axially above the valve stem guide 76 and encircles and sealingly contacts the valve stem 50 to create an air-tight seal that blocks actuating air from flowing downwardly from the air chamber 62 into the fluid chamber 34. In one embodiment, the lower and upper stem seals 78, 80 may be spring-energized to aid in maintaining their respective seals.
Referring to
An annular valve seat member 100 protrudes axially from the base surface 94 in a direction toward the upper surface 84 of the nozzle 22. In one embodiment, the valve seat member 100 and the nozzle 22 may be formed integrally as a single unitary piece. The valve seat member 100 includes a cylindrical outer surface 102, a cylindrical inner surface 104, and a valve seat 106 extending between the outer and inner surfaces 102, 104. As shown in
The cylindrical outer and inner surfaces 102, 104 are formed concentrically and extend coaxially along a central axis of the nozzle 22, which is aligned with the central axis of the fluid chamber 34 when the nozzle 22 is mounted to the fluid chamber member 32. The cylindrical outer surface 102 and the valve seat 106 define an upper outer edge 108 of the valve seat member 100. Additionally, the cylindrical inner surface 104 and the valve seat 106 define a lower inner edge 110 of the valve seat member 100. The valve seat 106 extends radially inward and axially downward from the upper outer edge 108 toward the lower inner edge 110. In this regard, the diameter of the cylindrical outer surface 102 defines a maximum outer diameter of the valve seat 106 at the upper outer edge 108. As best shown in
The valve seat 106 may be formed with a concave contour that substantially matches a convex contour of the valve stem tip 56, so as to enhance the sealing engagement between the valve seat 106 and the stem tip 56. Furthermore, in the embodiment shown, the cylindrical outer and inner surfaces 102, 104 of the valve seat member 100 may be formed with suitable axial dimensions such that the valve seat member 100 protrudes from the base surface 94 for an axial distance that permits the valve stem tip 56 to be substantially fully received within the blind bore 92 in the closed position, as best shown in
The annular valve seat member 100 opens to a dispensing outlet chamber 112 that extends axially toward and communicates with a dispensing outlet passage 114 extending through the conical tapered portion 90 of the nozzle 22. The outlet chamber 112 includes a cylindrical upper chamber portion 116 defined by the cylindrical inner surface 104, and a conical lower chamber portion 118 defined by a tapered inner surface of the nozzle 22. The outlet chamber 112 is configured to funnel liquid material into the outlet passage 114, which then directs the liquid material onto a substrate when the valve stem 50 is moved into the closed position.
Referring to
To move the valve stem 50 into the upward open position shown in
When the valve stem 50 is forced rapidly downward by the spring force into the closed position, the valve stem tip 56 exerts a compressive impact force on the valve seat 106. As described above, the valve stem tip 56 may be formed of a hard metallic material. Additionally, the valve seat member 100 may be formed of a material having a hardness that is less than that of the valve stem tip 56, such that the valve seat member 100 is configured to wear before the valve stem tip 56. For example, the nozzle 22, including the valve seat member 100, may be formed of a plastic such as an ultra high molecular weight polyethylene. Accordingly, repeated impact of the valve seat 106 with the valve stem tip 56 causes wear of the valve seat member 100 in an axial direction toward the dispensing outlet passage 114, as shown schematically in
Advantageously, the shape of the valve seat member 100 as shown and described herein enables the valve seat 106 to maintain a substantially constant surface area and angle of contact between the valve seat 106 and the valve stem tip 56 as the valve seat member 100 wears axially. In other words, the valve seat member 100 is “wear-compensated,” meaning that the shape of valve seat member 100 compensates for its own wear. As shown in
Further, as seen in
As described above, the volume of liquid material dispensed from the nozzle 22 is a function of the amount of energy transferred from the valve stem 50 to the liquid material when the valve stem tip 56 is lowered into contact with the valve seat 106 in the closed position. Additionally, the amount of energy transferred from the valve stem 50 to the liquid material is a function, in part, of the surface area of the valve seat 106. Accordingly, maintaining a substantially constant surface area and/or angle of contact of the valve seat 106 advantageously enables dispensing of liquid deposits with improved accuracy and repeatability. The wear behavior of the valve seat member 100 described above is enabled by the coaxial and concentric relationship of the cylindrical outer and inner surfaces 102, 104, such that the two surfaces 102, 104 extend in mutually parallel directions.
The useful life of the valve seat member 100 may be the period of use during which the width, and thus the surface area, of the valve seat 106 is maintained as substantially constant relative to the original surface area of the valve seat 106 prior to use. In this regard, the cylindrical outer and inner surfaces 102, 104 may be suitably formed with respective axial dimensions that dictate the duration of the period during which the width of the valve seat 106 is maintained. For example, in one embodiment, the valve seat member 100 may be formed such that the surface area of the valve seat 106 is substantially maintained until the upper outer edge 108 of the valve seat 106 is worn substantially flush with the base surface 94.
At the end of the useful life of the valve seat member 100, the nozzle 22 may be removed from the fluid dispensing apparatus 20 and replaced with a new nozzle 22 having an unworn valve seat member 100. As described above, the nozzle 22, including valve seat member 100, may be formed of a plastic material using injection molding methods. Accordingly, the nozzle 22 may be inexpensively formed while still presenting a useful life of adequate duration, thereby advantageously minimizing operational costs for the user.
While the present invention has been illustrated by the description of specific embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. The various features discussed herein may be used alone or in any combination. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the scope or spirit of the general inventive concept.
Claims
1. A nozzle for use with a fluid dispensing apparatus configured to dispense fluid and including a valve stem, the valve stem having a stem tip and being movable between an open position and a closed position, the nozzle comprising:
- a nozzle body; and
- a valve seat member coupled to the nozzle body and including an outer surface, an inner surface extending in a direction substantially parallel to a direction in which the outer surface extends, and a valve seat extending between the outer surface and the inner surface, the valve seat being configured to contact the stem tip in the closed position,
- wherein the valve seat has a valve seat surface area, and the valve seat member is configured to maintain the valve seat surface area as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
2. The nozzle of claim 1, wherein the valve seat further has an angle of contact at which the stem tip contacts the valve seat, and the valve seat member is configured to maintain the angle of contact as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
3. The nozzle of claim 1, wherein the valve seat member is annular and the outer surface includes a cylindrical outer surface and the inner surface includes a cylindrical inner surface extending coaxially with the cylindrical outer surface.
4. The nozzle of claim 1, wherein the valve seat and the outer surface of the valve seat member define an upper outer edge of the valve seat member, and the valve seat and the inner surface of the valve seat member define a lower inner edge of the valve seat member, the upper outer edge and the lower inner edge being configured to contact the stem tip in the closed position.
5. The nozzle of claim 1, further comprising:
- a bore extending through an upper surface of the nozzle body and having a base surface, wherein the valve seat member protrudes from the base surface in a direction toward the upper surface.
6. The nozzle of claim 5, wherein the passage includes a chamber at least partially defined by the valve seat member.
7. The nozzle of claim 1, further comprising:
- a passage extending through the nozzle body and the valve seat member, the passage configured to direct the fluid therethrough for dispensing.
8. The nozzle of claim 7, wherein the chamber includes a cylindrical chamber portion and a conical chamber portion extending therefrom, the cylindrical chamber portion being defined by the inner surface of the valve seat member.
9. The nozzle of claim 1, wherein the valve seat includes a contoured surface.
10. The nozzle of claim 9, wherein the valve seat member is configured to maintain a curvature of the contoured surface as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
11. The nozzle of claim 1, wherein the valve seat member is formed of a plastic.
12. A fluid dispensing apparatus configured to dispense fluid, comprising:
- a dispenser body;
- a valve stem operatively coupled to the dispenser body and having a stem tip, the valve stem being movable between an open position and a closed position; and
- a nozzle operatively coupled to the dispenser body, the nozzle including: a nozzle body; and a valve seat member coupled to the nozzle body and including an outer surface, an inner surface extending in a direction substantially parallel to a direction in which the outer surface extends, and a valve seat extending between the outer surface and the inner surface, the valve seat being configured to contact the stem tip in the closed position,
- wherein the valve seat has a valve seat surface area, and the valve seat member is configured to maintain the valve seat surface area as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
13. The fluid dispensing apparatus of claim 12, wherein the valve seat further has an angle of contact at which the stem tip contacts the valve seat, and the valve seat member is configured to maintain the angle of contact as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
14. The fluid dispensing apparatus of claim 12, wherein the valve seat member is annular and the outer surface has a cylindrical outer surface and the inner surface includes a cylindrical inner surface extending coaxially with the cylindrical outer surface.
15. The fluid dispensing apparatus of claim 14, wherein the valve seat is formed with a maximum outer diameter that is not greater than a maximum outer diameter of the stem tip.
16. The fluid dispensing apparatus of claim 12, wherein the valve seat and the outer surface of the valve seat member define an upper outer edge of the valve seat member, and the valve seat and the inner surface of the valve seat member define a lower inner edge of the valve seat member, the upper outer edge and the lower inner edge being configured to contact the stem tip in the closed position.
17. The fluid dispensing apparatus of claim 12, further comprising:
- a bore extending through an upper surface of the nozzle body and having a base surface, wherein the valve seat member protrudes from the base surface in a direction toward the upper surface.
18. The fluid dispensing apparatus of claim 12, further comprising:
- a passage extending through the nozzle body and the valve seat member, the passage configured to direct the fluid therethrough for dispensing.
19. The fluid dispensing apparatus of claim 18, wherein the passage includes a chamber at least partially defined by the valve seat member.
20. The fluid dispensing apparatus of claim 19, wherein the chamber includes a cylindrical chamber portion and a conical chamber portion extending therefrom, the cylindrical chamber portion being defined by the inner surface of the valve seat member.
21. The fluid dispensing apparatus of claim 12, wherein the valve seat member is formed of a plastic.
22. The fluid dispensing apparatus of claim 12, wherein the valve seat includes a contoured surface.
23. The fluid dispensing apparatus of claim 22, wherein the valve seat member is configured to maintain a curvature of the contoured surface as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
24. A method of dispensing fluid with a fluid dispensing apparatus including a dispenser body, a valve stem operatively coupled to the dispenser body and having a stem tip, the valve stem movable between an open position and a closed position, and a nozzle operatively coupled to the dispenser body and including a valve seat member having a valve seat, the method comprising:
- providing the valve stem in the open position in which the stem tip is spaced from the valve seat and in which the fluid collects in a space between the stem tip and the valve seat;
- moving the valve stem in a direction toward the valve seat to provide the valve stem in the closed position, and forcing the fluid with the stem tip through a passage extending through the valve seat member and the nozzle body to dispense the fluid; and
- while in the closed position, contacting the valve seat with the stem tip, including contacting an upper outer edge of the valve seat member defined by the valve seat and an outer surface of the valve seat member, and contacting a lower inner edge of the valve seat member defined by the valve seat and an inner surface of the valve seat member.
25. The method of claim 24, wherein the upper outer edge and the lower inner edge of the valve seat member define a valve seat surface area, and contacting the valve seat with the stem tip in the closed position includes maintaining the valve seat surface area as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
26. The method of claim 24, wherein the valve seat has an angle of contact at which the stem tip contacts the valve seat, and the valve seat member is configured to maintain the angle of contact as substantially constant during wear of the valve seat member caused by repeated contact of the stem tip with the valve seat.
Type: Application
Filed: Mar 2, 2016
Publication Date: Sep 15, 2016
Inventor: William MacIndoe (Exeter, RI)
Application Number: 15/059,109